One of these things is not like the others... That's right, it's the one in the middle. The knurling on the handle doesn't have equatorial scoring. So far as I can tell, just from dating, this handle originated in D series flare tips. I own 5 flare tips, A3, C1, C2, D2, and E1. The D2 and E1 have the simplified handle, while the A3 and the C models have the more intricate handle. This is, of course, a wild assumption, purely circumstantial. Can anybody corroborate this?
Basically, I'm asking anybody with a metal handle flare tip to tell me which kind of handle they have, as well as the date code It would be much appreciated.